Rectifying arrangement



C. STQKER RECTIFYING ARRANGENENT Filed May 6, 1943 LOS/WAN 1C. S TO CKE@ Patented Dec. 5, 1944 RECTIFYING ARRANGEMENT Closman P. Stocker, Lorain, Ohio, assigner of onehalf to E. M. Heavens Application May 6, 1943, Serial No. 485,836

21 Claims.

This invention relates to a rectifying arrangement and in particular to a system for supplying constant-voltage direct current from a variable? voltage source of alternating current.

The invention utilizes a leakage-reactance saturable transformer together with a capacitor and a polyphase rectifier in obtaining polyphase rectiiication from a single-phase alternating-current source. Under light loads the rectiers are supplied predominantly with single-phase voltage, the addition of load shifting the phases and thereby tending to increase the rectified voltage, compensating for the resistance and reactance voltage drops in the circuit. Changes in the single-phase supply voltage are likewise compensated vin the same transformer' by a combination of saturation and phase-shifting effects.

It is an object of my invention t supply constant-voltage rectified current from a variablevoltage alternating current source.

It is another object of my invention to produce polyphase rectification from a single-phase source.

Another object of my invention is to compensate for changes of load and changes of input voltage in a single control transformer.

A further object of my invention is to compensate a rectified voltage for changes of load and for changes of input voltage in a single compensating unit utilizing a leakage-reactance transformer.

Another object of my invention is to reduce the ripple voltage in the output of a rectifier energized from a single-phase source by producing polyphase rectification.

Still another object of my invention is to provide a compact system of regulated rectification having a high efliciency.

An additional object of my invention is to provide a regulated rectification system having improved dynamic characteristics.

Other objects and a better understanding of my invention may be had by referring to the following specification and claims in connection with the accompanying drawing in which Figure 1 is the circuit diagram of an embodiment of my invention with the leakage reactance transformer shown diagrammatically and with a winding on the leakage ux path,

Figure 2 is a modification of Figure 1 omitting the windings on the leakage llux path and show ing a filter on the rectified output, and

Figure 3 is an embodiment of my invention using a transformez` structure dierent from those shown in Figures 1 and 2, and using a condenserinput filter on the output.

With more particular reference to Figurel, there is shown a magnetic core having two fiux paths, the one including the core section I3, the other including the core section I4, with the section I2 being common to both flux paths. The flux path including the sections I2 and I3 is a substantially closed path which may become saturated under high magnetizing forces although I prefer to have a greater cross sectional area in section I2 than in section I3. By this construction I am able to operate core section I2 at a lower flux density than section I3. The iiux path through section I4 has a non-magnetic gap I5 in series and therefore represents a leakage path requiring a relatively high magnetizing force to highly magnetize the gap I5.

The two flux paths are magnetized by winding Il on the common section I2, winding I I in turn receiving its energy from the single-phase alternating current source I0. Thus the vectorial sum of the iiuxes through sections I3 and I4 is substantially equal to the flux in section I2, which is substantially proportional to the voltage of source I0.

Capacitor I9 is connected across Winding I'I on section I3. Winding I6 on core section I4- is connected to tap I8 on winding I`| and to the three-phase rectfers 22. The two other lines supplying the rectiiiers 22 are connected to winding Il. The direct current output of the rectiiiers 22 is supplied to terminals 29 and 2|.

The capacitive current through winding II shifts the phase of the flux through core section I3 with respect to the flux in section I4, the amount of phase shift varying in response to changes in the load on terminals 26 and '2I. In addition, the amount of flux through' core section I4 is determined to a considerable extent by the amount of load current which is drawn from terminals 20 and 2 I. I

When the direct current supplied fromA the output terminals 20 and 2| is of a low value, the rectification taking place is predominantlyr of a single phase and the rectified voltage roughly approximates the average value of the applied voltage of that phase. As the load current increases, the change in phase relationship between the fluxes in core sections I3 and I4 is used -to impress a polyphase or in this case a three-phase voltage on the rectifiers 22, and under aparticular load condition the three-phase voltage may .become nearlyj balanced. Under thiscondition the average value'of the rectified voltage rises `across it produces 2 nearly to the crest value oi' the applied voltage. Thus, by gradually changing from single-phase to polyphase rectication as the load is increased, an increase in rectified voltage is obtained oompensating for the voltage drop through the rectiers and other circuit resistances.

'I'he core section I3 is preferably operated at a high ilux density. and the magnetizing force some ilux through section I4 even when the load current is small. Capacitor I9 supplies part of the magnetizing current for section I3; under some conditions it may supply the entire reactive component oi this magnetizing current and when this is the case, the magnetizing force across the air gap Il may be relatively small, but responsive to changes in the voltage oi source I8. 'Ihese changes in voltage produce changes both in the magnitude and phase of the ilux through core section Il, and according to my invention I am able to use these iiux changes to maintain a constant rectied voltage across output terminals 28 and 2l in spite of variations in the voltage of source I3 and in spite of variations of therectified output current.

My control circuitv responds very rapidly to changes in load current or to changes in input voltage, and switching transients therefore have little eilect on the value of the rectiiled voltage across output terminals 28 and 2l.

Tap I8 maybe centrally located on winding I1 and the fluxes in the two core sections I3 and I4 may be ninety degrees out of phase with each other, in which case the interconnection of windings I6 and I1 becomes a conversion from two-phase to three-phase systems. It is not necessary for the tap I8 to be a center-tap, however, its optimum location being determined by the magnetic characteristics of the corematerial, therelative dimensions of the diilerent core sections and yso on. It is to be understood that the drawing is diagrammatic in nature and is not intended to show the proportions of the core structure or of the nonmagnetic gap, and that numerous departures from the proportions and conilgurations shown may be made withoutV departing from the true spirit and scope oi this invention.

In general, I 'prefer toy construct the core vso that the common portion of the core, whichfin the drawing carries the primary winding. has

a greater cross-sectional area the saturablev portion or the core.

Although the drawing` shows' a common typey of 'three-phase rectierconnction, other arrangements y'may be tiiiers neednot be threephase, 4as vother polyphase arrangements canbe adapted to theoperationof my invention.

In the arrangement of. Figure l2,- the winding I6 shownvon the core section I8 in Figure 1 is emitted. This omission does' not .necessarily change any of the essential feature'soi-the operation ci my invention asdescribed in connection with Figure 1. Since the'vectorial sum oi the iluxes in sections 'I3 and Il is substantially equal to the flux in-section I2,=,the. veiect of a winding. cn any one of the sections can. be substantially duplicated by the proper combination of windings on the other tion is-obtained by' properly locating tap` 26 on winding II and by the proper. 'phasing' and proportioning oi winding 25. Figure 2shows winding. I'l as a relatively high voltage winding used to impress d, on capacitorl a voltage sufficiently great to ,permit the use` of an economical size two sections.- 'This combina' Scott connection for of capacitor. Tap 21 on winding Il is located in accordance with the location of tap 28 to provide the proper voltage to the rectitiers 28 and to produce the operating characteristics described in coginseuction with Figure 1.

re 2 shows a simple inte rangemen interposed -between the rectinerlsn :Ind the ou: put terminals 28 and 2I. With this arrangement I am able to supply direct current output with a very small alternating current ripple component. The filtering can be accomplished with unusually small illter components because under heavy loads the polyphase rectincation produces a rectiiled voltage with a small ripple component, and it is not necessary to provide a large air gap 1n the magnetic circuit of filter inductance 28. Under heavy loads the impedance or the inductf ance 28 may be reduced by the direct current owing through it without increasing the A. C. component of the output voltage,'because as the load increases the A. C. component delivered by the rectiilers diminishes. Under light loads, the higher impedance of inductance 28 provides the necessary filtering and also holds the output voltage aty the average value of the rectiiied voltage and prevents the capacitor 23 from becoming charged to the crest value of the rectified voltage. In addition. with my invention I am able to produce a condition under which the no-load voltage across terminals 28 and 2| is not much greater than the normal output voltage. because ofthe wave-shape of the voltage supplied to the rectiers.

vBy using a relatively small nlter inductance, l am able to obtain improved dynamic characteristics in the output voltage, and sudden changes in load resistance produce relatively small nuctuations in the output voltage. When a large iilter inductance is used, the sudden removal of the load requires that the large amount of stored energy in the inductance must be stored in the lter condenser, and this requires a relatively great increase in the voltage across this condenser. The smaller energy storage of a small illter inductance produces a correspondingly smaller voltage increase.

- Figure 3 shows diagrammatically a somewhat diiIerent core structure than that shown in Figures 1 and 2'. In this figure, the energizing windingv Il is arranged on the central core member,

28. The core section 30 is a substantially closed flux path having the winding I1 on it. 'Ihe winding I'I is again shown supplying a relatively high voltage to the capacitor I8. Tap 3| is located to 'supply the required voltage to the rectier 22 and tap 32 is connected to winding I8 which supplies the out-of-phase component to the polyphase'rect'fiers. vWinding I8 is on core -section29 which has a non-magnetic gap I8.

Core section 29 in Figure 3 corresponds to core section il in Figures 1 and 2. Section 28 in Figure 3 is the core-portion common to both iiux paths and corresponds to section I2 in Figures 1 and 2. Section 30 is the saturable portion and corresponds to section I3 in Figures 1 and 2.

'Ihe fundamental principles of operation as described in connection with Figure 1 apply to Figure 3, the chief diilerences being quantitative rather than qualitative, because of the relative lengths of the flux paths.

Figure 3 also shows a dierent filtering arrangement than that shown in Figure 2. The capacitor 23 iny Figure 3 is connected directly across the output of the rectifiers, acting as a condenser-input illter. I have found that the regulating` .characteristics of my rectii'ying arrangement can be obtained not only with the choke-input filter as shown in Figure 2, but also with the condenser-input lter of Figure 3.

yAlthough I have described my invention with av certain degree of particularity, it is understood that the' present disclosure has been made only by `way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to withoutfdeparting from the spirit and the scope of the invention as hereinafter claimed.

I claim as my invention:

1. A rectifying arrangement, comprising in combination a polyphase rectifier; a leakage reactance type transformer and a capacitor, said transformer having a plurality of windings one of which is adapted to be connected across a source of single -phase alternating current, another of said plurality of windings being connected in parallel with the capacitor, and circuit means for connecting at least two of said plurality of windings to said polyphase rectiers, said transformer having a main flux path with a saturable portion and a leakage flux path magnetically disposed in parallel with the saturable portion, said capacitor supplying at least a part of the magnetizing current for the said saturable portion.

2. Ar rectifying arrangement, comprising in combination a polyphase rectifier; a leakage reactance type transformer and a capacitor, said transformer having a plurality of windings one of which is adapted to berconnected across a source of single phase alternating current, another of said plurality of windings being connected inparallel with the capacitor, and circuit means for connecting at least two of said plurality of windings to said polyphase rectifiers, said plurality of windings being proportioned to supply polyphase voltage to said rectifiers under normal loading, said transformer having a main flux path with a saturable portion and a yleakage flux path magnetically disposed in parallel with the saturable portion, said capacitor supplying at least a part of the magnetizing current for the said saturable portion.

SQA rectifying arrangement, comprising in combination, a polyphase rectifier, a transformer having a plurality of magnetic flux paths at least three of which operate at different flux densities, a capacitor and a plurality of winding means on at least two the plurality of magnetic flux paths, oneof the winding means being adapted for connection to a source of single phase alternating current, another of said winding means being connected in parallel with said capacitor, and circuit connecting means for energizing the polyphase rectiers from said plurality of winding means, said capacitor supplying at least a part of the magnetizing current for the flux path yhaving the highest flux density.

4. A rectifying arrangement, comprising in combination, a polyphase rectifier, a transformer having a plurality of magnetic flux paths at least three of which operate at different flux densities, a capacitor and a plurality of winding means on at least two of the plurality of magnetic flux paths, one of the winding means being adapted for connection to a source of single phase alternating current, another of said winding means' being connected in parallel with said capacitor, and circuit connecting means for energizing the polyphase rectiiiersfrom at least two of said plurality of winding means, said -capacltor supplying at least a part of the magnetizing current for the flux path having the highest flux density.

5. A control circuit adapted to be energized by a source of single phase alternating current, comprising in combination, a plurality of magnetic flux paths having differing characteristics, winding means on said flux paths adapted to be energized by said source to produce total flux linkages proportional to the voltage of said source, a capacitor supplying at least a part ofthe magnetizing current for one of said magnetic flux paths, output circuit means inductively related to at least two of said magnetic flux paths, and a polyphase rectifier energized by said output circuit means, one of said magnetic flux paths being a leakage flux path disposed magnetically in parallel with said fiux path receiving magnetizing current from the capacitor.

6. In combination with a single-phase source of alternating current, a magnetic core having a plurality of magnetic flux paths of differing magnetization characteristics, winding means on said flux paths connected to said source of alternating current, a capacitor supplying at least part of the magnetizing current for one of said flux paths, another of said magnetic flux paths constituting a leakage path, output circuit means inductively related to said flux paths, and a polyphase rectifier energized by said output circuit means.

'7. A rectifier circuit adapted to be energized by a source of single phase alternating current of varying voltage and to supply a variable direct current load with substantially constant voltage, said circuit comprising a magnetic core having a plurality of magnetic flux paths with a common portion, one of said flux paths having a nonmagnetic gap, another being a substantially closed magnetic circuit, first winding means on said core, said rst winding means being on the common portion, second Winding means on said core, a capacitor connected across said second winding means supplying at least part of the exciting current for said closedl magnetic flux path, output circuit means inductively related to said ux paths, and a polyphase rectifier energized by said output circuit means.

8. A rectifying arrangement comprising in combination a magnetic core having two magnetic flux paths with a common member, Winding means on said common member adapted to be energized from a source of single phase alternating current, one of said flux paths being saturable, the other having a non-magnetic gap therein, a winding on said saturable flux path, a capacitor connected across said Winding, output circuit means inductively related to both of said flux paths, and a polyphase rectifier connected to said output circuit means.

9. A rectifying arrangement comprising in combination a magnetic core having two magnetic flux -paths with a common member, winding means on said common member adapted to be .energized from a source of single phase alter- 10. A rectifying arrangement comprising ln combination a magnetic core having two magnetic flux -paths with a common member, winding means on said common member adapted to ,be energized from av source of single phase alternating current, one of said flux paths being saturable, the other having a non-magnetic gap therein, a winding on said saturable flux path, la capacitor connected across said winding, output circuit means inductively related to both of said flux paths, and a three-phase rectier connected to said output circuit means.

l1. A rectifying arrangement comprising in combination a magnetic core having two magnetic flux paths with a common member, winding means on said common member adapted to be energized from a source of single phase alternating current, one of said flux paths being saturable, the other having a non-magnetic gap therein, a winding on said saturable ux path, a capacitor connected across said winding, output circuit means inductively-related to bothL of said flux paths, and a three-phase rectifier connected to said output circuit means, said rectifying arrangement being adapted to shift from single-phase rectification under light loads to three-phase rectification under heavier loads.

12. A rectifying arrangement comprising in combination a magnetic core having two magnetic ilux paths with a common member, winding means on saidy common member adapted to be energized from a source of single phase alternating current, one of said flux paths being saturable, the other having a non-magnetic gap therein, a winding on said saturable iiux path, a flrst capacitor connected across said winding, output circuit means inductively related to both of said flux paths, a three-phase rectifier connected to said output circuit means, and a second capacitor connected across the direct current terminals of said three-phase rectifier.

13. A rectifying arrangement adapted to be energized by a source of single phase alternating current of varying voltage and to supply a variable direct current load with substantially constant voltage, comprising in combination with rectifying means, a capacitor, a transformer having a plurality of magnetic flux paths at least three of which operate at different iiux densities, and a plurality of winding means on at least two of the plurality of magnetic flux paths, one of the winding means being adapted for connection to the source of alternating current, another of said winding means being connected in parallel with said necting at least two of the plurality of winding means with said rectifying means, said transformer and capacitor being vso related that, at the normal loading of the arrangement, the respective transformer voltages of said windings have a ,polyphase relationship, said capacitor supplying at least a part of the magnetizing current for the ilux path having the highest flux density.

14. A rectifying arrangement, comprising in combination with rectifying means, a leakage reactance type transformer and a capacitor, said transformer having a plurality of windings, one of which 'is adapted to be connected across a source of single phase alternating current, another of said plurality of windings being ccnnected in parallel with the capacitor, and circuit means for connecting at least two of said plurality of windings to said rectifyingmeans, the reactance of said windings being so proportioned capacitor, and circuit means conin relation to each other and to a given normal load to be connected across the rectifying means that, when said tranfioijmer is energized by a source of single phase alternating current, the

voltages produced across said windings and eftion, a polyphase rectifier, a capacitor, a magnetic core having a plurality of flux paths with a common portion, one of said nuxpathsbeing saturable, another having a non-magnetic gap therein, a first winding on said common portion adapted to be energized from a source of singlephase alternating current, a second winding on said saturable flux path, said capacitor being connected substantially across said second winding, a third winding on the said flux path having the non-magnetic gap, and circuit means interconnecting said second and` third windings with the polyphaserectierand supplying it with polyphase alternating current under-the normal loading of the circuit.

16. A rectifying arrangement comprising in combination, a polyphase rectifier, a capacitor, a magnetic core having a plurality of flux paths with a common portion, one of said flux paths being saturable, another having a non-magnetic gap therein, a first winding on said common portion ada-pted to be energized from a single-phase source of alternating current, a second winding on said saturable flux path, said capacitor being connected substantially across said second winding, a third winding means being magnetically coupled to said rst winding means, and circuit means interconnecting said second and third windings means with the poly-phase rectier and supplying it with polyphase alternating current under the normal loading of the arrangement.

17. A rectifying arrangement comprising in combination, a magnetic core having a plurality of magnetic flux paths, one of said flux paths being a substantially closed magnetic circuit, another having a non-magnetic gap therein, first winding means on said core adapted to be energized by a single-phase source of alternating current to magnetize said magnetic ux paths, second winding means on said magnetic core, a capacitor connected to said second winding means, said arrangement being adapted to produce under normal loads a phase displacement between the voltage across the rst winding means and the voltage across the second winding means, and circuit means utilizing said phase 'displacement in energizing polyphase rectiiiers with polyphase current.

18. A rectifying arrangement comprising in combination, a magnetic core having a plurality of magnetic flux paths, one of said flux paths being a substantially closed magnetic circuit, another having' a non-magnetic gap therein, first winding means on said core adapted to be energized by a single-phase source of alternating current to magnetize said magnetic flux paths, sec-y ond winding means on said magnetic core, a capacitor connected to said .second winding means, said capacitor supplying at least part o1 the magnetizing current for said substantially closed magnetic circuit, and output circuit means energized by the flux in said magnetic ux paths supplying a polyphase rectier.

19. A rectifying arrangement, comprising in combination a polyphase rectifier, a capacitor and a leakage reactance type transformer having a closed magnetic core comprising iirst and second core portions and a leakage iiux path adapted to by-pass part of the ux of either core portion around the othercore portion, a primary winding on said first core portion adapted to be connected toa source of singlephase alternating current of uctuating voltage, a winding on said second core portion energizing said condenser and winding means on both iirst and second core portions connected to said polyphase recter.

20. A rectifying arrangement, comprising in combination a polyphase rectifier, a capacitor and a leakage reactance type transformer having a closed magnetic core comprising iirst and second core portions and a leakage ux path adapted to by-pass part of the iiux of either core portion around the other core portion, a primary winding on said first core portion adapted to be connected to a source of single phase alternating current of fluctuating voltage, a winding on said second core portion energizing said condenser and winding means on both rst and second core portions connected to said polyphase rectifier, the magnetic density at maximum predetermined input voltage of rst core portion being less than the maximum density of said second core portion.

21. A rectifying arrangement, comprising in combination a polyphase rectifier, a capacitor and a leakage reactance type transformer having a closed magnetic core comprising rst and second core portions, a primary winding on said rst core portion adapted to be connected to ya source of single phase alternating current of fluctuating voltage, a winding on said second core portion energizing said condenser and winding means on both rst and second core portions connected to said polyphase rectier, said core having magnetically disposed between windings on said rst and second core portions a magnetically permeable shunt with a non-magnetic gap portion.

CLOSMAN P. STOCKER. 

